UGT1A9与ABCG2的偶合作用调控甲氧基黄酮代谢及转运的机制研究

Methoxylated flavones are the active ingredients in the peel of the Citrus, they have biological activities of anti-cancer, anti-oxidation and prevention of cardiovascular disease. However, the poor oral bioavailability limits methoxylated flavones to be the health foods. The absorption and metabolism which mediated by transporters and metabolic enzymes are the main factors for oral bioavailability, we found that: UGT1A9 is the primarily metabolic enzyme metabolized 5-hydroxy-7-methoxyflavone and 5-hydroxy-7,8-dimethoxyflavone (5H7MF、5H7,8MF) to glucuronidation metabolites. Furthermore, the glucuronidation metabolites are still the substrate of transporter ABCG2. It shows that: the coupling of UGT1A9 and ABCG2 can regulate the metabolism and transport of methoxylated flavones and their glucuronidation metabolites and then affect their oral bioavailabilities. The HeLa-UGT1A9 cell model , the rat intestinal perfusion model and the rat jugular vein cannulation model were employed in order to clarify the mechanisms of regulation on metabolism and transport of methoxylated Flavones by the coupling of UGT1A9 and ABCG2 from the excretion of cellular metabolism, the biotransformation of intestinal and the pharmacokinetic of rats. The purpose of this study was to overcome the oral bioavailability barrier of methoxylated flavones and to develop the health foods from the Citrus. The study have both theoretical significance and practical values.

甲氧基黄酮为柑橘属植物果皮中的有效成分，具有抗癌、抗氧化、预防心脑血管疾病等活性。但较低的口服生物利用度限制了其开发成为保健食品。影响生物利用度的关键是吸收与代谢，而吸收与代谢是由转运蛋白和代谢酶共同介导的。我们研究发现：甲氧基黄酮（5H7MF、5H7,8MF）主要被代谢酶UGT1A9代谢生成葡糖醛酸化代谢物，且代谢物又被转运蛋白ABCG2外排至细胞外。这提示我们：UGT1A9与ABCG2的偶合作用可调控甲氧基黄酮的代谢及转运，影响口服生物利用度。本研究拟采用HeLa-UGT1A9细胞、大鼠在体肠灌流和大鼠颈静脉插管模型从体外细胞代谢外排、在体肠道生物转化和体内药代动力学三方面研究UGT1A9与ABCG2的偶合作用对甲氧基黄酮代谢及转运的影响及作用机制。本课题为克服甲氧基黄酮口服生物利用度屏障提供理论基础，更为富含甲氧基黄酮的柑橘属植物开发成为保健食品提供实验依据，具有理论意义和实用价值。

本研究以黄酮类化合物（5-羟基-7-甲氧基黄酮、5-羟基-7，8-二甲氧基黄酮）为研究对象，采用了HeLa-UGT1A9细胞模型、大鼠在体肠灌流模型和大鼠药代动力学模型从体外细胞代谢外排、在体肠道生物转化和体内药代动力学三方面研究药物代谢酶UGT1A9与药物转运蛋白ABCG2偶合作用对黄酮代谢及转运的影响及作用机制。细胞代谢外排研究结果表明，5H7MF及5H7,8MF均为药物代谢酶UGT1A9的底物，可在其作用下发生II相代谢反应，生成各自的葡萄糖醛酸化代谢产物；5H7MF及5H7,8MF均为药物转运蛋白ABCG2的底物，可被细胞膜上的ABCG2外排至细胞外，减少进入细胞的量。在体肠灌流吸收研究结果表明，5H7MF及5H7,8MF在大鼠十二指肠、空肠、回肠、结肠四个肠段的渗透性均较好，并且二者在上述四个肠段间的吸收无显著性差异，表明5H7MF及5H7,8MF在大鼠肠道无特定吸收部位。体内药代动力学结果表明，5H7,8MF 口服给药后，其在体内的吸收、分布都比较快，半衰期较长，消除较慢。本课题发现调控药物转运蛋白ABCG2可有效影响5H7MF及5H7,8MF的口服吸收，本课题为克服甲氧基黄酮口服生物利用度屏障提供理论基础，更为富含甲氧基黄酮的柑橘属植物开发成为保健食品提供实验依据，具有理论意义和实用价值。